Musical Note Frequency Chart & Calculator

Choose a note from C0 through B8, or enter a frequency from 0.001 to 50,000 Hz to find the nearest equal-tempered note and cents offset.

In Hz → Note mode, the Hz value shown is your input, not the exact target frequency of the nearest note. Switch to Note → Hz to calculate that target when it is within C0–B8. Outside that note-picker range, select a note manually. Frequencies outside MIDI 0–127 still return a mathematical note label, but not a valid MIDI note number. Values are rounded for display; calculations use unrounded numbers.

Changing A4 rescales this 12-TET chart; it does not select another temperament or retune an audio file. For example, A4 = 432 Hz puts C4 at about 256.869 Hz. Use the Audio Tools directory to choose a measurement or playback tool instead.

The A4 reference accepts 400–480 Hz. This page uses scientific pitch notation, where middle C is C4.

Common musical note frequencies

With A4 set to 440 Hz, middle C (C4) is about 261.626 Hz, A3 is 220 Hz and A5 is 880 Hz. In this 12-TET model, moving up an octave doubles frequency; moving down halves it. The common-note table below stays at A4 = 440 Hz even when you change the interactive chart.

For piano note frequencies, the 88-key range runs from A0 at 27.5 Hz to C8 at about 4,186.009 Hz in A440 12-TET. This is an ideal 12-TET reference, not a full tuning specification for an acoustic piano: string stiffness can require stretched octaves rather than exact 2:1 tuning. Both endpoints are included above; the chart extends farther to C0–B8 for synthesizers, analysis and other instruments. For the keyboard range, see the note table maintained for instrument builders.

What A4 = 440 Hz changes

ISO 16:1975 specifies 440 Hz for the tuning note A in the treble stave, and ISO lists the standard as current after its 2022 confirmation. That makes A4 = 440 Hz the sensible default for a general reference chart. It's still a reference, though; it doesn't claim that every ensemble, historical recording or instrument uses the same pitch.

If a session is tuned to A4 = 442 Hz, changing the reference recalculates the entire table. A4 becomes 442 Hz, A3 becomes 221 Hz and A5 becomes 884 Hz. Don't change the field just to make one unstable recording look centered; confirm the reference used by the source first.

How note-to-frequency conversion works

In twelve-tone equal temperament, an octave has a 2:1 frequency ratio and is divided into 12 equal semitone ratios. The UNSW acoustics reference expresses the MIDI-to-frequency conversion as:

frequency = A4 reference × 2^{(MIDI note − 69) / 12}

A4 is MIDI 69. The inverse calculation finds a fractional MIDI position from a frequency. Rounding that position selects the nearest note; the leftover logarithmic distance is reported in cents. One semitone is 100 cents, so 445 Hz at an A4 reference of 440 Hz is still nearest to A4, roughly 19.6 cents sharp.

Why octave labels sometimes disagree

This page uses scientific pitch notation: middle C is C4 and A4 is the reference A above it. Some synthesizers, DAWs and hardware use a different octave number for the same MIDI note. I'd match MIDI note 60 when octave labels disagree, and confirm the tuning reference separately. A MIDI note number is a key identifier, not a guarantee of one frequency: pitch bend, transposition or custom tuning can change the sound.

Sharps and flats can also name the same equal-tempered pitch. C♯4 and D♭4 both map to MIDI 61 and the same frequency here. The Sharps/Flats control changes spelling only; it doesn't touch the calculation.

Chart, pitch detector or spectrum analyzer?

A spectral peak isn't automatically the note you perceive. Musical sounds commonly include harmonics above the fundamental, and a strong harmonic can be taller than the fundamental in a spectrum. I'd use the table for known values, the detector for one live pitch and the analyzer when you need the full frequency picture.

Musical note frequency FAQ

What frequency is middle C?

Middle C is C4 in scientific pitch notation. It is approximately 261.626 Hz in twelve-tone equal temperament when A4 is set to 440 Hz, and it is MIDI note 60.

What musical note is 440 Hz?

At the default A4 = 440 Hz reference, 440 Hz is A4 and MIDI note 69. Changing the reference can change both the nearest note and its cents offset. At A4 = 442 Hz, 440 Hz is A4 about 7.85 cents flat; at A4 = 480 Hz, its nearest note is G4, about 49.36 cents sharp.

How do I convert Hz to the nearest note?

Enter the frequency in Hz → Note mode. The calculator finds its fractional position relative to A4, rounds to the nearest equal-tempered note and keeps the remaining distance as cents. A positive value is sharp of the displayed note; a negative value is flat.

Are C-sharp and D-flat the same frequency?

They are enharmonic equivalents in the 12-TET model used here, so C♯ and D♭ share a frequency and MIDI number. Other tuning systems can treat enharmonic spelling and pitch relationships differently.

Why does my synth call middle C C3 instead of C4?

Octave numbering is not universal across instruments and software. This chart uses scientific pitch notation, where middle C is C4. Match the MIDI number or frequency when your device uses another octave-label convention.